A collective delusion is the term most commonly used by social scientists to describe the relatively spontaneous spread of false beliefs that do not occur in an organized, institutionalized or ritualistic fashion.

Today, we live in a connected virtual community, and YouTube, Twitter, Facebook, and blogs, in addition to traditional media, are the medium through which community panic and delusions spread.

At this time there are two slow panics spreading through the community – fear of the H1N1 “swine” flu pandemic, and fear of the vaccine to prevent H1N1 flu. Regarding the pandemic itself – this is a real threat, it is just not known at this time how severe it will turn out to be. So far it is looking like another seasonal flu in severity, but with some different features, such as a greater tendency to severely affect otherwise healthy individuals.

A phantom limb sensation sometimes persists after amputation – the real limb is gone, but the person feels as if the limb remains. They can feel it, and even “move” it. Phantom limbs are one of my favorite examples of the fact that our brains construct an internal model of reality (and our bodies are included in that model), and like all biological processes, that process can go awry. Deprived of sensory and motor feedback from the missing limb, sometimes those bits of the brain (the insular cortex) that give us a sense of ownership and agency over a limb continue to function, manifesting a phantom limb to own and manipulate.

In rare cases, this process can lead to the emergence of a supernumerary phantom limb – a third (or fourth or fifth) arm that the person can feel and manipulate.

Researchers Moseley and Brugger recently published a study involving seven subjects with phantom limbs post-amputation. Their question was whether or not the subjects could be made to move their phantom limbs in anatomically impossible ways. They did this by giving them tasks to imagine with their phantom limbs, tasks that would be quick to accomplish by bending their wrist back in a normally impossible way.

Notorious cancer quack, Hulda Clark, died recently. However, it was not made public at the time that Clark, who claimed to have the cure for all cancers (and later the cure for all disease) died of cancer.

Her death certificate, which is now public, shows a contributing factors in her death to be multiple myeloma – a form of blood cancer. The immediate cause was listed as anemia, with hypercalcemia – both can be caused by multiple myeloma.

Clark was personally responsible for much human suffering and misery, and she lured in countless victims with her quackery and her false claims for a cure of cancer. She, of course, also tried to scare patients away from standard therapy for cancer. Of course, she herself had to die eventually of something, and cancer is the second leading cause of death, so it is not much of a coincidence that she died of cancer.

I doubt this fact will put much of a dent in the cancer quackery industry – an industry that does not trade much on evidence and reason to begin with, but rather fear, distrust, desperation, and false hope.

The anti-vaccine community are a loose collection of individuals and organizations who, at their core, are dedicated to the notion that vaccines are bad. There is some variation of opinion within the anti-vaccinationists, but not much. Some claim that vaccines do not work at all, while other acknowledge some benefit. Some try to be coy by saying they are just asking questions (sure, like the 9/11 truthers are “just asking”), while others come right out and make demonstrably false claims, like vaccines cause autism. But they all cluster around the opinion that vaccines are toxic (in some way) and that they cause harm.

What is remarkable about the anti-vaccine crowd is their consistency in talking points. One might call it message discipline (enough to make Republicans jealous) but I think that implies more deliberate coordination than there is evidence for. I may be wrong in this, but I think it is enough to say that they all travel in the same virtual circles and play off each other’s rhetoric and arguments. They are a political/ideological community, and such communities are more plugged in today because of Web 2.0 than ever before.

I’m not just talking about slogans, like “Green our Vaccines”, which are designed for widespread use. Reading the various anti-vaccine websites and authors you begin to see a pattern of specific talking points coming in waves. Squalene has been in vaccines as an adjuvant for years, yet suddenly many of the anti-vaccine sites are squawking about squalene. I have not tracked down the original source of the squalene flap – it spread so quickly through the anti-vaccine blogs.

A recent study, as reported in the New Scientist, purports to catch the placebo effect in the act using functional MRI scanning. This is an interesting study, and does for the first time show a neurophysiological correlate to reported placebo decreases in pain reporting.

However, reporting of the study highlights, yet again, widespread misconceptions about the nature of placebo effects – specifically that there are many placebo effects, not one placebo effect. Any reference to “the” placebo effect is therefore misleading – it is a convenient short hand, but unfortunate given prevailing misconceptions.

What most people mean when they say “the” placebo effect is a real physiological effect that derives from belief in the effects of a treatment – a mind-over-matter effect. However, the placebo effect, as it is measured in clinical trials, has a very specific operational definition. It is any and all measured effects other than a physiological response to the treatment itself.

The complementary and alternative (CAM) or integrative medicine phenomenon that has arisen over the last couple of decades primarily involves the creation of a separate subculture within medicine. The primary defining characteristic of the CAM subculture is a lack of dedication to a culture of science-based practice.

The strength of mainstream medicine, which should strive for the ideals of science-based medicine, is that it mostly does. There is a culture of ultimate respect for the scientific evidence. The application, of course, is imperfect – but the ideal is there. If you bring enough high quality evidence to bear, you can change the standard of care, how everyone else is practicing medicine.

Like freedom and democracy, science-based medicine is messy in all the ways that human cultures are messy, and it requires vigilance and constant self-examination. Right now the systems of quality control and self-correction within medicine are straining to keep up with the rapid advances in medical knowledge and technology. We are, in some ways, victims of our own success. The evidence-based medicine (EBM) movement is primarily about codifying strategies for keeping up with the exploding evidence.

Remember Ida? Back in May of this year, scientists unveiled a beautiful 95% complete skeleton of a 47 million year old extinct primate. This specimen, because of its age and quality, was sure to add a significant piece to the puzzle of primate evolution. And yet, it seems, the scientists got a little too over-excited and blew the popularizing of this find.

Ida was unveiled with much fanfare, complete with a dedicated website, a book, and a documentary. Some of the media soaked up the hype, while other outlets caught on to the fact that the scientific community was not getting being it, and in fact were trying to pull back on the reigns.

Well now a new paper in the journal Nature by an independent group of scientists makes skepticism of the original interpretation of Ida official.

A new study published online in Environmental Health Perspectives shows no correlation between blood mercury levels in 2-5 year old children and autism or developmental delay. This study adds to the growing evidence that environmental exposure to mercury, from any source, is not a risk factor for autism.

The study looked at 452 children aged 2-5 (which is a robust sample) with either autism spectrum disorder (ASD), other developmental delay (DD), or typically developed (TD). They found that children with ASD and DD had lower levels of blood mercury than TD controls. They further found that ASD and DD children tended to eat less fish, and as fish is by far the most significant source of mercury exposure, this explains their lower levels.

The researchers then adjusted for reported exposure to fish as well as other known sources of mercury and found that the adjusted level of mercury were the same for all groups. The levels were also similar to established national norms, meaning that the population being studied and the methods used are likely representative.

One of the core principles of scientific skepticism is that human perception, information processing, and memory, while powerful, are deeply flawed. We need rigorous controls in observation and analysis in order to compensate for these flaws and arrive at reliable conclusions. Otherwise we are slaves to the vagaries of our own neurological function.

One of the coolest and most dramatic examples of our flawed perception is the phenomenon known as inattentional blindness. Before I go any further, for any of you who have not seen the basketball demonstration, take a look at it now before you continue reading. See if you can count how many times the players in the white shirt pass the ball around. This is more tricky than it seems.

The Huffington Post, an online news source, from its creation has embraced anti-scientific pseudomedicine. It has been a home for a number of anti-vaccine cranks, as well as promoters of all kinds of medical nonsense. Occasionally there appears a brief flower of reason (token efforts at best) – for example our own Michael Shermer recently publicly called out Bill Maher on his anti-vaccine nonsense in the HuffPo. Here’s the money quote:

As well, Bill, your comments about not wanting to “trust the government” to inject us with a potentially deadly virus, along with many comments you have made about “big pharma” being in cahoots with the AMA and the CDC to keep us sick in the name of corporate profits is, in every way that matters, indistinguishable from 9/11 conspiracy mongering.

But these brief incursions of reason aside, the HuffPo has been in continual free fall into medical woo since its inception. Although in retrospect it has been hopeless for a long time, for me it crossed the veil into complete and utter advocacy of woo when it hired Dana Ullman as a regular blogger.

Ullman is notorious as a homeopath and internet lurker, spreading undiluted nonsense as far and wide as his typing fingers can manage. I will have to resist the urge to deconstruct every bit of medical misdirection he will spread with his new forum – that would be a full time job for one blogger. But as I have already received numerous requests to take a look at his latest post, I will give him some deserved skeptical attention.